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The Ars Technica article Vice President may tell NASA to accelerate lunar landings ends with:

And on Thursday, NASASpaceFlight.com reported that the agency is considering skipping a critical test that is part of the large Space Launch System rocket's development plan. Before the first rocket launches, NASA had planned to send the entire core stage of the rocket, with its four engines, to Stennis Space Center for a "Green Run" test firing, including an eight-minute burn that would mimic the rocket's ascent into orbit. This process would have taken about six months.

Now, the agency is considering whether to skip that test entirely in favor of just a short, five-second test firing on the launchpad at Kennedy Space Center. This would increase the risk of some kind of problem during launch but shave as much as six months from the development timeline. This is another indication of the Trump administration's desire to assess all avenues for accelerating NASA's spaceflight programs.

Question: Why would an 8-minute burn result in a 6-month delay? Or am I oversimplifying and/or misunderstanding?

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    $\begingroup$ It takes a lot of effort to set up tests. The actual test may only last seconds, but it takes a lot of effort to set it up logistically, with equipment, personnel, instrumentation, safety measures, etc... Then it may also take a lot of time to analyze the data, validate it, quantify uncertainty, and certify it. I’ve often found that it takes a lot more time to validate results than to create them. $\endgroup$ – Paul Mar 23 at 0:20
  • $\begingroup$ @Paul the decision is between an 8-minute burn and a 5-second burn. It seems to be the length of the burn that is correlated with the six month delay. I'll add more highlighting to make that clearer. Of course the longer burn would generate a much larger quantity of data and perhaps push more systems to their limits requiring more scrutiny. Thanks! $\endgroup$ – uhoh Mar 23 at 0:24
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    $\begingroup$ Aren't they SSMEs? they'd probably need to strip down and rebuild them after a full duration burn, perhaps they've lost the skillset since they canned the STS? $\endgroup$ – JCRM Mar 23 at 0:42
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    $\begingroup$ It’s an additional burn at a separate location. That requires an additional shipping step, install & checkout, etc. $\endgroup$ – Bob Jacobsen Mar 23 at 0:50
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    $\begingroup$ It's good to see my hero Holly Ridings pictured in the Ars Technica article. $\endgroup$ – Organic Marble Mar 23 at 0:55
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The answer to your question is right here in the following section:

Before the first rocket launches, NASA had planned to send the entire core stage of the rocket, with its four engines, to Stennis Space Center for a "Green Run" test firing, including an eight-minute burn that would mimic the rocket's ascent into orbit. This process would have taken about six months.

Now, the agency is considering whether to skip that test entirely in favor of just a short, five-second test firing on the launchpad at Kennedy Space Center.

The prep work, transportation to Stennis, set-up, test firing, and transport back could easily take six months. Testing the core stage on the pad at KSC, where it would have to go anyway, requires no additional time.

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    $\begingroup$ @uhoh The word 'send' does, though. Most people would infer one from the other. $\endgroup$ – Diego Sánchez Mar 23 at 16:02
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    $\begingroup$ @uhoh You surely don't expect them to put one of those things in the trunk and just drive it to Mississippi overnight. The whole thing is implied by 'send'. $\endgroup$ – Diego Sánchez Mar 23 at 18:44
  • $\begingroup$ @DiegoSánchez Ah! I see the disconnect. The first sentence "...is right there in the quoted text:" should read "...is right here." I keep looking in my quoted text and not finding it. I've made a small edit. $\endgroup$ – uhoh Mar 23 at 22:54
  • $\begingroup$ @DavidRatti Thanks for your insight! The article's euphemistic use of "send" doesn't really make it clear what a huge amount of work is involved. $\endgroup$ – uhoh Mar 23 at 23:00
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Focusing on schedule, an obvious candidate for an “alternate approach” is the Stage Green Run test campaign long in planning for the Stennis Space Center.

"skipping the trip to Stennis" - they don't have to ship the stage to Stennis, just to KSC for launch, which they would have to do in any case.

They probably would have done the Flight Readiness Firing at KSC anyway.

So, this is a flagrant case of skipping pre-planned testing to try and keep the schedule! What could go wrong?

Reference: article linked in the question.

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